C#•4y ago

Modify property of object in List [Answered]

I have a struct like this:

public struct MyStruct
{
    public ulong Id { get; set; }

    public string MyProperty { get; set; }
}

public struct MyStruct
{
    public ulong Id { get; set; }

    public string MyProperty { get; set; }
}

And I have a

List<MyStruct>

List<MyStruct>

. I want to modify

MyProperty

MyProperty

for a certain

MyStruct

MyStruct

in the list, using the

Id

Id

property. I tried this:

MyList.Where(x => x.Id == id).ToList().ForEach(x => x.MyProperty = myVariable);

MyList.Where(x => x.Id == id).ToList().ForEach(x => x.MyProperty = myVariable);

But it didn't work.

TheBoxyBear•10/14/22, 9:34 PM

MyStruct is a struct so you can't change the value of properties

TheBoxyBear•10/14/22, 9:34 PM

Loop or not

TheBoxyBear•10/14/22, 9:36 PM

Ir you need to edit the properties, make it a class to make it a reference type

TheBoxyBear•10/14/22, 9:36 PM

$ref

TTheBoxyBear $ref

MODiX•10/14/22, 9:36 PM

https://cdn.discordapp.com/attachments/364492811489509376/692833980650881084/pass-by-reference-vs-pass-by-value-animation.gif

mtreit•10/14/22, 9:40 PM

Yes, use a class if you want mutable properties. In general structs should be immutable.

mtreit•10/14/22, 9:41 PM

Now, knowing that a struct is passed by value (meaning a copy is made when you access it), you COULD achieve what you want even using structs - by mutating the copy and then putting that copy back into the list.

mtreit•10/14/22, 9:41 PM

However, this is doing a bunch of extra work for no good reason - just use a class instead.

mtreit•10/14/22, 9:53 PM

You could also achieve this with ref locals if the data was an array instead of a list. Again though, I would just use a class or a record.

BujjuOP•10/14/22, 10:37 PM

Thanks

AccordAPP•10/14/22, 10:38 PM

This post has been marked as answered!